The present invention is related generally to techniques for performing real time backup and copying of data, and specifically to techniques for updating data in the event of an emergency.
Conventional real time remote copy technology provides real time backups of system data in data storage controllers. Backups are prepared and forwarded to a system distant from the system being backed up. The backup data is updated in real time, so that it can be used in order to recover quickly from trouble, such as system faults and the like, for example. Backup data (“secondary data”) is expected to be located as far away from the data (“primary data”) of a working system (“primary system”) in order to prevent damage to the secondary data caused by a wide spread disaster such as an earthquake, for example. In order to keep the secondary data to be completely coincident with the primary data after updating the primary data, it is also necessary to proceed to the next step in the primary system processing only after confirming that the secondary data has been updated (“perform a synchronous remote copy”).
However, the farther a storage device for storing the secondary data is located, the longer the data transfer time and therefore, the communication time for the confirmation of the completion of updating the secondary data, can become. As a result, the processing performance of the primary system deteriorates with increasing distance.
What is needed are improved techniques for performing data backup.